Step 1: Click on the Setup tab at the top and click Wireless Settings on the left side

Step 2: Click on Manual Wireless Network Setup

Step 3: Scroll down the page to "Wireless Security Mode".
This is the section where you set the wireless password (Pre-Shared Key). You can input a new password; be sure to click Save Settings at the top of the page once complete.

Method 3

If you’ve registered your router with mydlink, you may log in to the mydlink web portal at www.mydlink.com to modify your router’s settings.

Step 1: Go to https://www.mydlink.com

Step 2: Log in to mydlink with your existing mydlink account and password.

Step 3: Choose the router from My Devices. Go to Settings.

Step 4: Go to Basic Settings to modify your password. You may also click “Show password” in order to display the password on your screen.

Step 5: Select Apply if you have made changes to Settings.

Step 6: Select Yes if you would like to apply the new settings to the router. It will take at least 80 seconds to save the changes and reboot the router.